1. Technical Field
The present invention relates to a method of manufacturing a magnetic head slider, and in particular, to a method of manufacturing a magnetic head slider having a magnetic head section composed of thin-films.
2. Related Art
The recording density of a magnetic disk device has been advanced remarkably in recent years and is still increasing, and a recording method called longitudinal recording in which magnetic data is written horizontally with respect to the disk surface has been mainly adopted. In the longitudinal recording, however, as the magnetic poles repel each other, it is difficult to realize a higher density. Even if a recoding density can become higher by making the film thickness of the recording medium thinner so as to suppress repelling of the magnetic poles, a problem of heat disturbance that the recording magnetization becomes unstable due to the heat energy of the room temperature is unavoidable. As such, a magnetic disk device utilizing perpendicular recording, capable of increasing the recording density, is realized recently.
As perpendicular recording, a method of recording data with used of a head (single magnetic-pole type) arranged perpendicularly to a hard disk has been used. In this method, a magnetic field is applied to a recording layer interposed between a lining soft magnetic layer of a bilayer recording medium and a single magnetic-pole head so as to magnetize the magnetic body of the recording medium in a direction perpendicular to the disk surface to thereby record data. This method has a characteristic that a demagnetizing field acting on between adjacent bits is decreased as the linear recording density is increased, so that the stability of the recording magnetization is maintained.
Now, a method of manufacturing a magnetic head slider having a thin-film magnetic head of a perpendicular recording method according to a conventional example, disclosed in Japanese Patent Laid-Open Publication No. 2004-39148 (Patent Document 1), will be described with reference to FIGS. 14 to 24.
A magnetic head according to Patent Document 1 is formed such that a magnetic head section 110 having a multi-layered thin-film structure is formed on a base 100 as shown in FIG. 15A (step S101 in FIG. 14, wafer step), by means of existing thin-film processes including a film deposition technique such as plating and sputtering, a patterning technique utilizing photolithography and etching, and a lapping technique such as machining and lapping, in a multi-layer forming step. The configuration of the multi-layered magnetic head section 110 formed in the multi-layer forming step will be described with reference to FIGS. 17A and 17B. 17B is a side sectional view of the magnetic head section 110, and FIG. 17A is a sectional view in which the magnetic head of FIG. 17B is viewed from the left side.
The magnetic head section 110 is configured such that on a substrate 101 (base 100) made of a ceramic material such as AlTiC (Al2O3.TiC), an insulating layer 102 made of aluminum oxide for example (Al2O3; hereinafter simply referred to as “alumina”), a read head unit 110A which performs a reading process with use of magneto-resistance effect (MR), and a write head unit 110B which performs a writing process by means of a perpendicular recording method, and an overcoat layer 114 made of alumina for example, are layered in this order. Hereinafter, the read head unit 110A and the write head unit 110B will be described in more detail.
The read head unit 110A is configured such that a lower shield layer 103, a shield gap film 104, an upper shield and return yoke layer (hereinafter simply referred to as “return yoke layer”) 106 are laminated in this order, for example. In the shield gap film 104, an MR element 105 serving as a magnetic reading device is buried such that one end face thereof is exposed on the air bearing surface S (flying surface) described later. The lower shield layer 103 and the return yoke layer 106 are mainly for magnetically shielding the MR element 105 from the environment. The lower shield layer 103 and the return yoke layer 106 are made of a magnetic material such as nickel-iron alloy (NiFe (hereinafter simply referred to as “permalloy (trade name)”); Ni: 80 weight %, Fe: 20 weight %).
Further, the shield gap film 104 works to magnetically and electrically separate the MR element 105 from the lower shield layer 103 and the return yoke layer 106. The shield gap film 104 is made of a non-magnetic and non-conductive material such as alumina, for example. The MR element 105 performs a reading process by means of giant magneto-resistive effect (GRM) and a tunneling magneto-resistive effect (TMR), for example.
The write head unit 110B is configured such that the return yoke layer 106, a gap layer 107 and a yoke layer 109 in which a thin-film coil 108 is buried, a magnetic pole layer 111 magnetically connected with the return yoke layer 106 via the yoke layer 109 through an aperture 107K formed in the gap layer 107, an insulating layer 112, and a write shield layer 113, are layered in this order. As described above, the return yoke layer 106 works to magnetically shield the MR element 105 from the environment in the read head unit 110A, and also works to flow back a magnetic flux output from the magnetic pole layer 111 via a hard disk (not shown) in the write head unit 110B. The return yoke layer 106 is made of a magnetic material such as permalloy (Ni: 80 weight %, Fe: 20 weight %), for example.
The gap layer 107 is disposed on the return yoke layer 106, and is configured to include a gap layer portion 107A in which the aperture 107K is formed, a gap layer portion 107B disposed on the gap layer portion 107A and covering parts between the windings of the thin-film coil 108 and the surrounding area, and a gap layer portion 107C disposed to partially covering the gap layer portions 107A and 107B. The gap layer portion 107A is made of a non-magnetic and non-conductive material such as alumina, for example. The gap layer portion 107B is made of photoresist (photosensitive resin) or spin-on-glass (SOG) which shows flow characteristics when heated, for example. The gap layer portion 107C is made of a non-magnetic and non-conductive material such as alumina or silicon oxide (SiO2), and the thickness thereof is larger than that of the gap layer portion 107B.
The thin-film coil 108 mainly works to generate a magnetic flux for writing. The thin-film coil 108 is made of a high-conductive material such as copper (Cu) for example, having a winding structure which spirally winds around the linked part of the return yoke layer 106 and the yoke layer 109. It should be noted that FIG. 17B shows only a part of a plurality of windings constituting the thin-film coil 108. Further, the yoke layer 109 works to magnetically link the return yoke layer 106 and the magnetic layer 111, and is made of a magnetic material such as permalloy (Ni: 80 weight %, Fe: 20 weight %).
Further, the magnetic pole layer 111 mainly works to contain a magnetic flux generated in the thin-film coil 108, and outputs the magnetic flux to a magnetic disk (not shown). The magnetic pole layer 111 is made of an iron-cobalt alloy (FeCo), an iron-based alloy (Fe-M; M is a metal element of 4A, 5A, 6A, 3B, 4B group), or nitride of each of the alloys. The insulating layer 112 mainly works to magnetically and electrically separate the magnetic pole layer 111 and the write shield layer 113, and is made of a non-magnetic and non-conductive material such as alumina. The write shield layer 113 mainly works to magnetically shield the magnetic pole layer 111 from the environment, and is made of a magnetic material such as permalloy (Ni: 80 weight %, Fe: 20 weight %).
Next, the detailed configuration of the main part of the thin-film magnetic head will be described with reference to FIG. 18. FIG. 18 shows an enlarged plan configuration of the main part of the magnetic head section 110. That is, in FIG. 18, the magnetic head section shown in FIG. 17A is viewed from the above. It should be noted that the return yoke layer 106, the magnetic pole layer 111, and the write shield layer 113 will be described herein as the main part of the magnetic head section.
The return yoke layer 106, the magnetic pole layer 111, and the write shield layer 113 are formed such that one end portion of each of them is exposed on the cut-off surface S′ when a bar block is cut off from a multi-layered body in which the magnetic head section 110 is stacked on the base 100, as described later. A portion, exposed on the cut-off surface S′, of the magnetic pole layer 111 is formed as an ultrasmall tip portion 111A having a certain width defining a recording truck width on a disk. The tip portion 111A is formed such that the width thereof is reduced from the back end portion 111B. Further, the return yoke layer 106 and the write shield layer 113 are formed in a shape that the end portions in the width direction are removed in the cut-off surface S′. More specifically, the return yoke layer 106 and the write shield layer 113 form tapered inclined surfaces 106A and 113A which are inclined by a predetermined angle with respect to the cut-off surface S′, respectively. The shapes of the layers 106, 111 and 113 are formed in the multi-layer forming step (wafer step), respectively.
Then, as shown in FIG. 15B, a bar block 130 is cut off from the base 100 (layered body) in which the magnetic head section 110 having the above structure is stacked (step S102 of FIG. 14). In this step, the bar block 130 is cut at the cut-off surface S′ shown in FIG. 18. Then, the cut-off surface S′ is lapped to a position forming a flying surface S (step S103 of FIG. 4) as shown in the sectional view of FIG. 19 and in the top view of the FIG. 10, to thereby adjust the MR element 105 which is a read element and the length of the tip portion 111A of the magnetic pole layer 111 which is a write element. Thereby, as shown in the perspective view of FIG. 22, the end portions in the width direction of the return yoke layer 106 and the write shield layer 113 are removed to be in a tapered shape (inclined surfaces 106A and 113A) on the flying surface S of the magnetic head section 110. However, an insulator 115 such as alumina is buried on the tip sides and in the surroundings of the tapered inclined surfaces 106A and 113A, as shown in FIG. 21.
Then, with respect to the bar block 130 shown in FIG. 16A, an ABS having a predetermined shape is formed on the flying surface S of a magnetic head slider 131 (step S104 in FIG. 14). Then, the bar block 130 is cut into respective magnetic head sliders 131 by a slider cutter (step S105 of FIG. 14). Thereby, a magnetic head slider 131 is formed in which the base 100 forms a slider portion 100 and the magnetic head section 110 is provided at the end thereof, as shown in FIG. 16B.
Then, a head gimbal assembly is formed with the magnetic head slider 131 manufactured as described above, and further, a magnetic disk device is formed by incorporating the head gimbal assembly. Here, writing operation by the magnetic head slider incorporated in the magnetic disk device will be described with reference to FIG. 23A.
When writing data, in the magnetic head section 110, when an electric current flows in the thin-film coil 108 of the write head unit 110B through an outside circuit not shown, a magnetic flux J1 is generated in the thin-film coil 108. The generated magnetic flux J1 is stored in the magnetic pole layer 111 via the yoke layer 109, and is output from the end surface (flying surface S) of the magnetic pole layer 111 to the write layer 302 of the magnetic disk 300, and then is flown back to the return yoke layer 106 through the back layer 301. At this time, a magnetic field (perpendicular magnetic field) for magnetizing the write layer 302 in a direction orthogonal to the surface thereof is generated according to the magnetic flux J1 output from the magnetic pole layer 111, and with the write layer 302 being magnetized by the perpendicular magnetic field, information is written on the magnetic disk 300.
In contrast, when reading data, when a sense current flows in the MR element 105 of the read head unit 110A, the resistance value of the MR element 105 varies according to the signal magnetic field for reading generated from the write layer 302 of the magnetic disk 300. By detecting the resistance variation as changes in the sense current, information written on the magnetic disk 300 is read.
In the magnetic head section 110 of the Patent Document 1, as the both edge sides of the return yoke layer 106 has two tapered inclined surfaces 106A and the both edge sides of the write shield layer 113 has two tapered inclined surfaces 113A, it is possible to prevent generation of track erase which is an unnecessary writing process, and to improve reliability of the magnetic recording operation.
It should be noted that FIG. 23B shows another conventional magnetic head section in which no tapered inclined surface is formed at the end portions in a width direction of the return yoke layer 106 and the like, indicating the flow of a magnetic flux when writing of the magnetic head section. Further, FIG. 24 schematically shows the shape of the return yoke layer (conventional; no tapered surface, Patent Document 1; with tapered surfaces), and measurement results relating to correlation with the magnetic field intensity. First, in the conventional magnetic head section as shown in FIG. 23B, the return yoke layer 206 has no tapered inclined surface 106A as in the Patent Document 1, and the return yoke layer 206 is formed to be in a complete rectangle having two corners 206B. Further, the write shield layer 213 also has no tapered inclined surface 113A, and is formed to be in a complete rectangle shape having two corners 231B.
In the conventional magnetic head section as shown in FIG. 23B, when a magnetic flux J2 output from the magnetic pole layer 211 is flown back to the return yoke layer 206, the reflux magnetic flux J2 locally concentrates on the corners 206B of the return yoke layer 206. Similarly, the magnetic flux J2 from the magnetic pole layer 111 and an outside magnetic flux locally concentrate on the corners 213B of the write shield layer 213. As such, as shown in FIG. 24, the magnetic field intensity extremely increases locally in the periphery of the respective corners 206B and 213B of the return yoke layer 206 and the write shield layer 213. Consequently, an unintentional perpendicular magnetic field is generated due to the magnetic flux concentrated on the corners 206B and 213B, whereby an unnecessary writing process is performed to the magnetic disk 300, so that track erase is caused. This may reduce the reliability of the magnetic recording operation.
In contrast, as shown in FIG. 23A, as the return yoke layer 106 has tapered inclined surfaces 106A and the write shield layer 113 has tapered inclined surfaces 113A respectively in the magnetic head section 110 of Patent Document 1, there is no corner which may induce concentration of a magnetic flux, so that magnetic field intensity is never concentrated locally in the periphery of the inclined surfaces 106A and 113A. Accordingly, in the Patent Document 1, concentration of a magnetic flux which has been a problem in the conventional magnetic head section is prevented, and so the rate of occurrence of an unnecessary writing process is lowered, whereby it is possible to prevent generation of track erase and to improve reliability of the magnetic writing operation.    [Patent Document 1] JP 2004-39148 A
However, in the method of manufacturing a magnetic head slider disclosed in Patent Document 1, as tapered inclined surfaces are formed on the both end sides in a width direction of the return yoke layer and the write shield layer in the thin-film layered process (wafer step), steps in forming a multi-layer such as patterning become complicated. This leads to problems that the manufacturing time becomes longer and the manufacturing costs increase. Further, as the shape is formed in the thin-film layered process, an insulator is actually buried in the surroundings of the tapered inclined surfaces, so that the possibility that such a part contacts the magnetic disk increases. As a result, the reliability of the magnetic disk device cannot be improved.